This invention relates to an improved air freshener gel wherein an aqueous medium containing a volatile air freshener component is gelled by a new gelling agent composition. More particularly, the invention relates to a new gelling agent composition comprising carrageenan, locust bean gum, and ammonium chloride, wherein the carrageenan contains at least 40%, by weight of the carrageenan, kappa carrageenan.
Air freshener gels and their gelling agents are well known. Generally, air freshener gels comprise an aqueous medium containing a volatile air freshener component and a gelling agent which gels the largely aqueous medium. Air freshener gels provide an ideal medium for freshening the air and are popular consumer products.
Air freshener gels operate by continuously releasing the air freshener components from the gel by the room temperature evaporation of the aqueous medium within the gel. The volatile air freshener components can include disinfectants, bactericides, insecticides, and odoriferous materials, or oils which provide a pleasant odor and/or reduce unpleasant odors.
Heretofore, in accordance with U.S. Pat. No. 2,927,055, air freshener gels were prepared by employing as a gelling agent a formulation of carrageenan, locust bean gum, and potassium chloride in conjunction with sodium carboxymethylcellulose. In accordance with the patent, the components and proportions of components of the formulation of gelling agent range as follows in percent, by weight of the complete gel formulation: 0.75 to 1.8% carrageenan, 0.2 to 0.75% locust bean gum, 0.1 to 0.75% potassium chloride, and 0.15 to 0.7% sodium carboxymethylcellulose. In accordance with U.S. Pat. No. 2,927,055, the air freshener gel is prepared by blending the components of the gelling agent in the dry state, adding the blended components to cold water, and heating the components to 180.degree.-190.degree. F. with stirring, until the solids are completely dispersed. The aqueous dispersion is then cooled to 170.degree. F. and the preblended air freshener components added with stirring until a uniform dispersion results, tranferring the dispersion to a molding means, and cooling to produce the formed gel.
In accordance with Canadian Pat. No. 895,825, air freshener gels can be prepared with gelling agents comprising mixtures of specific carrageenan fractions, namely kappa and iota carrageenan. Specifically, the Canadian Patent teaches the use of a gelling agent composition in air freshener gels comprising kappa and iota fractions of carrageenan in which the weight ratio of the respective components is between about 1.5:1 and about 7:1. The Canadian Patent also teaches the optional addition of calcium and/or potassium ions in the form of their chlorides to the gelling agent composition. The optional addition of calcium or potassium ions to the gelling agent, in accordance with the Canadian Patent, is particularly useful when the gelling agent contains high concentrations of kappa carrageenan.
The air freshener gels obtained in accordance with U.S. Pat. No. 2,927,055 and Canadian Pat. No. 895,825, have been found to exhibit undesirable gel syneresis, i.e., separation of the aqueous medium from the gel caused by gel contraction and/or inadequate water gel strength.
It has now been found that gel syneresis problems associated with the gelling agent combinations set forth in U.S. Pat. No. 2,927,055 and Canadian Pat. No. 895,825, have been overcome by the improved gelling agent composition of the present invention. It was unexpectedly found that the three component gelling agent composition of the present invention, when used to prepare air fresheners gels, yields an air freshener gel exhibiting negligible syneresis and improved water gel strength.